Bollettino valanghe

Northwest Coastal

Jan 23 – 24, 2017Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 10 years ago

Pericolo valanghe

Tue
Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Conditions are improving, but the consequence of triggering a large persistent slab avalanche warrants a cautious approach to steep open terrain.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2
    Lingering wind slabs are expected to remain reactive to human triggering in steep wind loaded terrain features.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–3
    It may still be possible to trigger avalanches on buried weak layers (Dec 25, Jan 5th, Jan 12th surface hoar) ...or have a smaller avalanche 'step down' and trigger one of these layers.

Confidence

High - Due to the number and quality of field observations

Weather Forecast

TUESDAY: Cloudy with isolated flurries along the coast, 20-40 km/h southwest winds, freezing level up to 500 m.WEDNESDAY: Flurries with up to 5 cm of new snow, 30-50 km/h southwest winds, freezing level up to 700 m.THURSDAY: Flurries with 5-10 cm of new snow, 50-70 km/h southwest winds, freezing level up to 800 m.

Avalanche Summary

Over the weekend there were several reports of natural and skier triggered wind slabs in the size 1-1.5 range, primarily on west aspects. Evidence of a previous widespread natural avalanche cycle during last week's storm was also reported, where size 2 to 3 avalanches released in both the storm snow as well as on deeper surface hoar layers (likely the January 5th). Triggering wind slabs as well as lingering persistent slabs remains a possibility at higher elevations.

Snowpack Summary

Light flurries and moderate winds have formed fresh wind slabs above 40-60 cm of settled storm snow from last week. Freezing levels reached 1200 m during the storm, which has left a hard supportive crust at lower elevations. At this point there is some uncertainty as to how deeper persistent weak layers are responding to the recent loading and warming. Several weak surface hoar and facet interfaces were reactive during the storm, but have shown signs gaining strength since. This includes the January 5th layer about 50 cm deep and the December 25th layer up to a metre deep. These are not typical conditions for this coastal region, and it will take more time to gain confidence about the distribution and likelihood of triggering these deeply buried weak layers.

Regioni coperte